<?php
/*
 *  $Id: Db2.php 7490 2010-03-29 19:53:27Z jwage $
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the LGPL. For more information, see
 * <http://www.doctrine-project.org>.
 */

/**
 * Doctrine_Sequence_Db2
 *
 * @package     Doctrine
 * @subpackage  Sequence
 * @author      Konsta Vesterinen <kvesteri@cc.hut.fi>
 * @license     http://www.opensource.org/licenses/lgpl-license.php LGPL
 * @link        www.doctrine-project.org
 * @since       1.0
 * @version     $Revision: 7490 $
 */
class Doctrine_Sequence_Db2 extends Doctrine_Sequence
{
	/**
	 * Returns the next free id of a sequence
	 *
	 * @param string $seqName   name of the sequence
	 * @param bool              when true missing sequences are automatic created
	 *
	 * @return integer          next id in the given sequence
	 * @throws Doctrine_Sequence_Exception
	 */
	public function nextId($seqName, $ondemand = true)
	{
		$sequenceName = $this->conn->quoteIdentifier($this->conn->formatter->getSequenceName($seqName), true);
		$query = 'SELECT NEXTVAL FOR ' . $sequenceName . ' AS VAL FROM SYSIBM.SYSDUMMY1';

		try {
			$result = $this->conn->fetchOne($query);
			$result = ($result) ? $result['VAL'] : null;
		} catch(Doctrine_Connection_Exception $e) {
			if ($onDemand && $e->getPortableCode() == Doctrine_Core::ERR_NOSUCHTABLE) {
				try {
					$result = $this->conn->export->createSequence($seqName);
				} catch(Doctrine_Exception $e) {
					throw new Doctrine_Sequence_Exception('on demand sequence ' . $seqName . ' could not be created');
				}

				return $this->nextId($seqName, false);
			} else {
				throw new Doctrine_Sequence_Exception('sequence ' .$seqName . ' does not exist');
			}
		}
		return $result;
	}

	/**
	 * Return the most recent value from the specified sequence in the database.
	 * This is supported only on RDBMS brands that support sequences
	 * (e.g. Oracle, PostgreSQL, DB2).  Other RDBMS brands return null.
	 *
	 * @param string $sequenceName
	 * @return integer
	 * @throws Doctrine_Adapter_Db2_Exception
	 */
	public function currId($sequenceName)
	{
		$sql = 'SELECT PREVVAL FOR '
		. $this->quoteIdentifier($this->conn->formatter->getSequenceName($sequenceName))
		. ' AS VAL FROM SYSIBM.SYSDUMMY1';

		$stmt   = $this->query($sql);
		$result = $stmt->fetchAll(Doctrine_Core::FETCH_ASSOC);
		if ($result) {
			return $result[0]['VAL'];
		} else {
			return null;
		}
	}

	/**
	 * Gets the last ID generated automatically by an IDENTITY/AUTOINCREMENT column.
	 *
	 * As a convention, on RDBMS brands that support sequences
	 * (e.g. Oracle, PostgreSQL, DB2), this method forms the name of a sequence
	 * from the arguments and returns the last id generated by that sequence.
	 * On RDBMS brands that support IDENTITY/AUTOINCREMENT columns, this method
	 * returns the last value generated for such a column, and the table name
	 * argument is disregarded.
	 *
	 * The IDENTITY_VAL_LOCAL() function gives the last generated identity value
	 * in the current process, even if it was for a GENERATED column.
	 *
	 * @param string $tableName OPTIONAL
	 * @param string $primaryKey OPTIONAL
	 * @return integer
	 * @throws Doctrine_Adapter_Db2_Exception
	 */
	public function lastInsertId($tableName = null, $primaryKey = null)
	{
		$this->_connect();

		if ($tableName !== null) {
			$sequenceName = $tableName;
			if ($primaryKey) {
				$sequenceName .= "_$primaryKey";
			}
			$sequenceName .= '_seq';
			return $this->lastSequenceId($sequenceName);
		}

		$sql = 'SELECT IDENTITY_VAL_LOCAL() AS VAL FROM SYSIBM.SYSDUMMY1';
		$stmt = $this->query($sql);
		$result = $stmt->fetchAll(Doctrine_Core::FETCH_ASSOC);
		if ($result) {
			return $result[0]['VAL'];
		} else {
			return null;
		}
	}
}